Essential fatty acids, degree of unsaturation, and effect of corn (maize) oil on the serum-cholesterol level in man .
Essential fatty acids, degree of unsaturation, and effect of corn (maize) oil on the serum-cholesterol level in man .
Year: 1957
Authors: A Keys, J Anderson, F Grande.
Publication Name: The Lancet.
Publication Details: Page 66.
Abstract:
Early studies by these researchers established that dietary fats differ in their effect on serum cholesterol. Certain vegetable fats appeared to exert a hypocholesterolemic effect, while intake of saturated fat exerted a hypercholesterolemic effect. The researchers speculated that hypercholesterolemia might be an expression of a deficiency in the intake of the essential fatty acid linoleic acid (LA), which is found in high concentrations in vegetable oils. However, in contrast, a low incidence of heart disease has been observed in Eskimos and Norwegians who consume large quantities of fish oils. Because fish oils contain little or no LA, this would support the hypothesis that the degree of unsaturation of the fatty acid may be responsible for cholesterol reducing effects. The objective of the present study was to compare the effect of fish oil, corn oil, sunflower oil, and butter fat on serum cholesterol values. Twenty-six healthy men were randomly allocated to one of four groups (n=7, n=7, n=6, n=6). Each group consumed a diet enriched with butterfat, sardine oil, corn oil, or sunflower oil for a 2-3 week period in a cross-over design. The test oils were fed in quantities of 100 g/daily as part of a diet constant in all other respects and designed to provide an average of 100g of protein, 300mg of cholesterol, and 40g of mixed food fat in addition to the test oils. Dietary fat represented 39.8% of total calories in each diet. Samples of blood were drawn at the end of each week and analyzed for serum total-cholesterol in the alpha- and beta-lipoprotein fractions. Mean serum total-cholesterol values following the butterfat diet were 52.0mg/100ml higher than the corn oil diet, 35.0mg/100ml higher than the sunflower oil diet, and 39.8 mg/100ml higher than following the sardine oil diet. Serum total cholesterol values increased following the change from corn oil to sunflower oil diet, and decreased following the reverse change, with the average difference being 9.3mg/100ml. Total serum cholesterol values also rose following the change from corn oil to sardine oil, and decreased following the reverse change, with the average difference being 20.2 mg/100ml. Finally, the level of cholesterol in serum beta-lipoprotein fractions were correlated to these changes. *Dietary fat effects on serum cholesterol values in man appears to not simply be an inverse function of the essential fatty acid content, or degree of unsaturation of the fatty acids in the diet. Additional research is therefore necessary to clarify additional factors that may contribute to these effects.
